diff --git a/maidroid_core/cores/ocr.lua b/maidroid_core/cores/ocr.lua
index ce22bc6..6301df1 100644
--- a/maidroid_core/cores/ocr.lua
+++ b/maidroid_core/cores/ocr.lua
@@ -4,20 +4,29 @@
 ------------------------------------------------------------
 
 local maidroid_instruction_set = {
+	-- popular (similars in lua_api) information gathering functions
 	getpos = function(_, thread)
 		local pos = thread.droid.object:getpos()
 		return true, {pos.x, pos.y, pos.z}
 	end,
 
-	beep = function(_, thread)
-		minetest.sound_play("maidroid_beep", {pos = thread.droid.object:getpos()})
-		return true
+	getvelocity = function()
+		local vel = self.vel
+		return true, {vel.x, vel.y, vel.z}
+	end,
+
+	getacceleration = function(_, thread)
+		local acc = thread.droid.object:getacceleration()
+		return true, {acc.x, acc.y, acc.z}
 	end,
 
 	getyaw = function(_, thread)
 		return true, thread.droid.object:getyaw()
 	end,
 
+	-- other info functions
+
+	-- popular actions for changing sth
 	setyaw = function(params, thread)
 		if #params ~= 1 then
 			return false, "wrong number of arguments"
@@ -29,6 +38,48 @@ local maidroid_instruction_set = {
 		thread.droid.object:setyaw(p)
 		return true
 	end,
+
+	-- other actions
+	jump = function(params, thread)
+		-- test if it can jump
+		local droid = thread.droid
+		if droid.vel.y ~= 0
+		or droid.vel_prev.y ~= 0 then
+			return true, false
+		end
+
+		-- get the strength of the jump
+		local h = tonumber(params[1])
+		if not h
+		or h <= 0
+		or h > 2 then
+			h = 1
+		end
+
+		-- play sound
+		local p = droid.object:getpos()
+		p.y = p.y - 1
+		local node_under = minetest.get_node(p).name
+		local def = minetest.registered_nodes[node_under]
+		if def
+		and def.sounds then
+			local snd = def.sounds.footstep or def.sounds.dig
+			if snd then
+				p.y = p.y + .5
+				minetest.sound_play(snd.name, {pos = p, gain = snd.gain})
+			end
+		end
+
+		-- perform jump
+		droid.vel.y = math.sqrt(-2 * h * droid.object:getacceleration().y)
+		droid.object:setvelocity(droid.vel)
+		return true, true
+	end,
+
+	beep = function(_, thread)
+		minetest.sound_play("maidroid_beep", {pos = thread.droid.object:getpos()})
+		return true
+	end,
 }
 
 
@@ -61,6 +112,8 @@ end
 local function on_start(self)
 	self.object:setacceleration{x = 0, y = -10, z = 0}
 	self.object:setvelocity{x = 0, y = 0, z = 0}
+	self.vel = {x = 0, y = 0, z = 0}
+	self.vel_prev = self.vel
 
 	local parsed_code = pdisc.parse(get_code(self) or dummycode)
 	self.thread = pdisc.create_thread(function(thread)
@@ -77,9 +130,13 @@ end
 
 local function on_step(self)
 	local thread = self.thread
-	if thread.stopped then
-		thread:try_rebirth()
+	if not thread.stopped then
+		return
 	end
+	self.vel_prev = self.vel
+	self.vel = self.object:getvelocity()
+
+	thread:try_rebirth()
 end
 
 local function on_resume(self)
@@ -92,6 +149,7 @@ end
 
 local function on_stop(self)
 	self.thread:exit()
+	self.thread = nil
 
 	self.object:setvelocity{x = 0, y = 0, z = 0}
 end