TeleOperation (using mouse) Plugin for RosSharp. Add to the RosConnector Object. Inputs are the topic name, camera, a prefab for pointer and the base link of the robot.

ShowMousePosition.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ShowMousePosition : MonoBehaviour
{
    public GameObject mousePointer;
    public bool clipToInteger;
    public Camera cam;

    private bool active = true;
    // Start is called before the first frame update
    void Start()
    {
        mousePointer = Instantiate(mousePointer, new Vector3(), Quaternion.identity);
    }

    // Update is called once per frame
    public void Update()
    {
        if(active) {
            mousePointer.transform.position = getPointerPosition();
        }
    }

    public Vector3 getPointerPosition()
    {
        if (clipToInteger)
            return snapPosition(getWorldPoint());
        else
            return getWorldPoint();
    }

    public Vector3 getWorldPoint()
    {
        Ray ray = cam.ScreenPointToRay(Input.mousePosition);
        RaycastHit hit;
        if (Physics.Raycast(ray, out hit))
        {
            return hit.point;
        }
        return Vector3.zero;
    }

    public Vector3 snapPosition(Vector3 original)
    {
        Vector3 snapped;
        snapped.x = Mathf.Floor(original.x + 0.5f);
        snapped.y = Mathf.Floor(original.y + 0.5f);
        snapped.z = Mathf.Floor(original.z + 0.5f);
        return snapped;
    }

    public void Deactivate()
    {
        active = false;
        HidePointer();
    }

    public void Activate()
    {
        active = true;
        ShowPointer();
    }

    private void ShowPointer()
    {
        mousePointer.active = true;
    }

    private void HidePointer()
    {
        mousePointer.active = false;
    }
}

TeleOperator.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
namespace RosSharp.RosBridgeClient
{
    public class TeleOperator : UnityPublisher<MessageTypes.Geometry.Twist>
    {
        public Camera cam;
        public GameObject mousePointer;
        public Transform baseLink;

        private ShowMousePosition mousePosition;
        private MessageTypes.Geometry.Twist message;
        private bool active;

        public void Deactivate()
        {
            active = false;
            mousePosition.Deactivate();
        }
        
        public void Activate()
        {
            active = true;
            mousePosition.Activate();
        }
        
        // Start is called before the first frame update
        protected override void Start()
        {
            base.Start();
            InitializeMessage();
            mousePosition = cam.gameObject.AddComponent<ShowMousePosition>();
            mousePosition.cam = cam;
            mousePosition.mousePointer = mousePointer;
            Deactivate();
        }

        public void Update()
        {
            if (Input.GetMouseButtonDown(0)) {
                Activate();
            }
            if (Input.GetMouseButtonUp(0)) {
                Deactivate();
            }
        }
        
        // Update is called once per frame
        private void FixedUpdate()
        {
            if (active) {
                UpdateMessage();
            } else {
                message.linear = GetGeometryVector3(new Vector3());
                message.angular = GetGeometryVector3(new Vector3());
                Publish(message);
            }
        }

        private void UpdateMessage()
        {   
            Vector3 currPose = baseLink.position.Unity2Ros();
            Vector3 localGoalPose = baseLink.InverseTransformPoint(
                mousePosition.getPointerPosition()
            ).Unity2Ros();
            localGoalPose[2] = 0;
            float distance = localGoalPose.sqrMagnitude;
            float linearVel = Mathf.Clamp(0.15f * distance, -0.1f, 0.3f);
            float angularVel = Mathf.Clamp(
                Mathf.Atan2(localGoalPose[1], localGoalPose[0])*Mathf.Rad2Deg,
                -45, 45 
            );                
            message.linear = GetGeometryVector3(new Vector3(linearVel, 0, 0));
            message.angular = GetGeometryVector3(new Vector3(0, 0, angularVel));
            Publish(message);
        }

        private void InitializeMessage()
        {
            message = new MessageTypes.Geometry.Twist();
            message.linear = new MessageTypes.Geometry.Vector3();
            message.angular = new MessageTypes.Geometry.Vector3();
        }

        private static MessageTypes.Geometry.Vector3 GetGeometryVector3(Vector3 vector3)
        {
            MessageTypes.Geometry.Vector3 geometryVector3 = new MessageTypes.Geometry.Vector3();
            geometryVector3.x = vector3.x;
            geometryVector3.y = vector3.y;
            geometryVector3.z = vector3.z;
            return geometryVector3;
        }
    }    
}